Preoperative DTI is an imaging modality that allows identification of pathways inside the brain that control important functions needed to support an independent life (movements, speech, understanding, reading, writing, naming of objects, vision etc).
Identification of these pathways before the operation, helps us in adjusting our surgical strategy, and is also helpful in quantifying the risks of our operations as precisely as possible. With this information in mind we are in better position to discuss with our patients the benefits and risks of different options of management.  
Preoperative DTI image